The present invention relates to a car telephone apparatus.
A prior art car telephone apparatus generally uses an erasable programmable read only memory (EPROM) of an ultraviolet ray type as a nonvolatile memory means for storing software for control of the apparatus.
Accordingly, when it is desired to change the contents of the software already written in the EPROM, it has been necessary to once erase the contents of the EPROM and then to rewrite data contents with use of a special writing means. In addition, the erasing operation of the written contents requires ultraviolet rays to be irradiated onto the EPROM itself, which may adversely affects other parts located in the vicinity of the EPROM. For the purpose of avoiding the influences of the ultraviolet rays on the other parts and improving its workability, it become necessary to once dismount the EPROM from the car telephone apparatus. For easy detachable mounting of the EPROM, it is common practice to mount the EPROM chip per se to a socket.
FIG. 4 schematically shows a block diagram of a control system of a prior art car telephone apparatus. In the drawing, the illustrated control system includes a CPU 21 for controlling the car telephone apparatus, an EPROM 22 as a nonvolatile memory for storing therein software describing a series of control procedures or means, a RAM 23 as a memory for temporarily storing therein arithmetic operation and data for control execution, an I/O port 24 for direct control of peripheral devices within the car telephone apparatus, and a socket 25 for mounting of the EPROM 22 thereto. Various sorts of control of the car telephone apparatus is sequentially carried out under control of the CPU 21 according to the contents of the EPROM 22.